Any ideas on this?

I am a web developer who will be in west africa for the next 6 months, and i have an idea for a web/mobile application that allows urgent news and information to be pushed to the web and down to subscribers mobile phones via text messages. The problem i have now is getting a way of sending text messages free to subscribers, since i want to service free of charge (for obvious reasons) and i also want the service to be self sustaining without burning a hole in my pocket. Thanks guys for your ideas on this.